where is Ricci tensor, is its contraction, is metric tensor of spacetime, and is stress-energy tensor.

Einstein added this cosmological constant to his field equation to make the universe stationary (neither expanding nor contracting) which it works when the cosmological constant has so called Einstein value

,

where is Newtonian gravitational constant, is density of space, and is speed of light in vacuum.

Contents

Historical background

In 1915 Einstein introduced the field equation that placed into balance and found equal the curvature at one side and mass on the other. He hoped that the equations of general relativity would determine a single universe model without any beginning or end. For reasons he could never make clear, he found universe so conceived particularly satisfying and he managed to find a solution to his own equations that specified universe of that sort, static and unchanged forever.[1][note 1] A.G. Riess declares that Einstein's original idea was to have constant amount of energy in the space.[3] When in 1920s Russian mathematician A.Friedman (1924)[4] and Belgian catholic priest and professor of physics G.Lemaître (1927)[5] independently found that Einstein's gravitational field equations of general relativity have non-static cosmological solution[1] implying an expanding or collapsing universe[6], Einstein, wishing to cancel out expansion, suggested modification to his field equations by adding a so-called cosmological term.[7][note 2] Before long, after Hubble's interpretation of new discoveries as expanding universe in 1929, the role of cosmological constant aiming to allow static homogeneous solutions to field equations in presence of matter seemed finished. Einstein called "the biggest blunder of my life".[7]

Revival of the cosmological constant vs. property of the correct metric

In general, a positive causes acceleration to the universe expansion, whereas negative and ordinary matter tend to decelerate it.[7] When the Supernova Cosmology Project Collaboration and High-Z Supernova Team Collaboration started their research at the beginning of 1990s, both prevailing mainstream cosmological models assumed decelerating universe scenarios. The processing of collected data from research observations however indicated that the universe is accelerating and requires something like non-zero cosmological constant.[3] The first paper on new discovery was submitted in May 1998[8] and in December the same year the new discovery of the accelerating universe was declared to be "Breakthrough of the Year" in the journal Science.[9][10]

According to J.Hartnett, it would be fair to state that most cosmologist would like the requirement for cosmological constant to disappear altogether. He interprets its extremely small value as a possible evidence for fine-tuned universe.[6]
The 2011 Nobel Laureate in Physics, Brian P. Schmidt was asked in 2011 the question "what is causing the universe to expand at accelerating rate?" which he answered by words that it is a big mystery why space should have energy at all, people around the world are scratching their heads to figure out but as of today there has not been lot progress yet.[11]

It has been however declared that Carmeli's theory which has no explicit cosmological constant implies its equivalence of = 1.934 × 10-35 s-2 and this value is supposed to be in excellent agreement with measurements.[12] The 'force' pushing the universe apart, which invokes the ideas about dark energy is more correctly just a property of the correct metric.[13]

Notes

↑The contemporary atheistic scientists such as S.Hawking believe there is no room for creator in the universe which has no boundary or edge whereas in universe which had beginning we could suppose it had a creator.[2] See also: Antipathy to the idea of beginning

↑cf."the 'cosmological constant' ... [also] had the effect of balancing the gravitational attraction that would otherwise cause the universe to collapse"[2]

References

↑ 2.02.1Edgar Anrews (2010). Who made God? Searching for a theory of everything.. Carlisle, PA, USA: EP Books, 98, 100. ISBN 978-0-85234-707-2. “Stephen Hawking puts it thus: 'So long as teh universe had a beginning, we could suppose it had a creator. But if universe is really completely self-contained, having no boundary or edge, it would have neither beginning not end; it would simply be. What place then for creator?'”

↑James Glanz (18 December 1998). BREAKTHROUGH OF THE YEAR: ASTRONOMY: Cosmic Motion Revealed 2156-2157. Science Magazine. DOI:10.1126/science.282.5397.2156a. “In 1998, astronomers peered into the universe and found that it is flying apart ever faster, suggesting that Einstein was right when he posited a mysterious energy that fills "empty" space, and in fact that most of the energy of the universe is in this form. Two independent teams of astronomers found that not only is there too little matter in the universe to ever halt the expansion of the universe on its own, but the outward motion appears to be speeding up, not slowing down. At the same time, the finding raises such profound questions about the nature of space that cosmologists are wondering whether the ultimate fate of the universe can ever be known for certain. We therefore name their findings, which transform our view of the universe and pose fundamental new questions for physics, as Breakthrough of the Year for 1998.”